1. Technical Field
The invention pertains to the construction and manufacture of voice coil assemblies, where particular emphasis is placed on reducing the weight of such devices.
2. Description of the Prior Art
Voice coil assemblies customarily include a voice coil carrier, a voice coil, a centering membrane, and stranded wires. Customarily, the tubular voice coil carrier is connected to the voice coil. Axially spaced from the voice coil is a centering membrane that is also connected to the voice coil carrier by means of an adhesive seam. The centering membrane, which extends radially from the longitudinal extension of the voice coil carrier, has either an accordion-like or a corrugated contour, depending on the design. Each of the two voice coil wires of the voice coil is connected to one of the two stranded wires by a solder connection. To form the voice coil assemblies, which are often prefabricated for use in the manufacture of loudspeakers, essentially two manufacturing methods have been employed.
According to the first known method, the voice coil is first wound around the support and baked; the inside diameter of the neck of the loudspeaker membrane or diaphragm is then connected to the outer diameter of the voice coil carrier. After the connection of the diaphragm to the voice coil carrier, the voice coil wires are connected to the stranded input wires by solder connections. Once an adhesive bead is applied to the neck of the diaphragm, the centering membrane is pushed over the voice coil and adhered to the outer diameter of the neck of the diaphragm. If the solder points were not previously adhered to the diaphragm before the centering membrane was pushed on, they are now glued to the underside of the diaphragm.
According to another known method, first the voice coil is connected to the voice coil carrier and the voice coil wires are connected to the stranded wires at the solder points. The solder points are then adhered to the voice coil carrier. Next, the centering membrane is pushed from the end of the voice coil carrier, which is not connected to the diaphragm, onto the voice coil carrier and attached to the voice coil carrier by means of an adhesive seam which is located between the adhesion sites for the solder points and the voice coil. This process has the disadvantage, with respect to the first process, that a relatively large amount of adhesive is required for attachment of the centering membrane to the voice coil carrier.
This can be attributed to the fact that the centering membrane in the second process must have a relatively large inside diameter in order to prevent damage to the voice coil when pushing the centering membrane over the voice coil. In this process, it is not possible to push the centering membrane from the end of the voice coil carrier, which will be later joined to the diaphragm. Of course, a small inner diameter of the centering membrane is possible; however, this would mean that the centering membrane must be located between the solder points and the end of the voice coil carrier, which will later be joined to the diaphragm. Pushing the centering membrane with a smaller inside diameter farther downward over the solder points and then attaching it to the voice coil carrier is not possible since the smaller inside diameter would destroy or remove the attachment of the solder points to the voice coil carrier. Finally, the second method has the disadvantage, relative to the first method, that due to the additional placement of the solder points on the voice coil carrier, the joints must be completely adhesive-tight, in order to prevent the penetration of adhesive (which is needed for attachment of the solder points) to the inside of the voice coil carrier. This additional sealing will result in increased weight. To complete the voice coil assembly, according to the second method, the voice coil carrier will also be connected to the diaphragm. However, the connection of voice coil carrier and diaphragm can take place at a time when the voice coil carrier and the centering membrane are already mounted in a loudspeaker housing.
Whereas the first method requires a great deal of manual effort and thus is relatively labor-intensive compared to the other methods, vibration coil devices according to the other methods have the added disadvantage that due to the need for attachment of the solder points to the voice coil carrier, these vibration coil supports have a 4-5 mm larger design height compared with voice coil carriers which are used in voice coil assemblies according to the first method. Except for the fact that the large design height of the voice coil carrier is also associated with increased weight, this additional design height also acts as an additional spring, so that the application of force onto the diaphragm is negatively influenced. The latter is expressed, in particular, in a deteriorated height reproduction. Regardless of the latter aspects, voice coil assemblies which are produced according to the two known methods have the general disadvantage that a total of three adhesive seams is needed to form them, and specifically for the connection of diaphragm and of the centering membrane to the voice coil carrier and also for attachment of the solder points to the diaphragm and to the voice coil carrier. Therefore the invention is based on the problem of defining a weight-reducing voice coil assembly and also an automated method for its manufacture.